Gregory A. Robinson and David E. Miller

Peer Reviewed

Abstract: There are many geodetic datums in use throughout the world today. Each of these datums serves as a reference surface for the mapping, charting and geodetic work done in a specific geographical area. Each datum is defined by fitting a specific ellipsoid to the earth in such a manner as to minimize departures of this reference model from the geoid over the area of concern. Historically, these datums have been relatively oriented. Consequently, the position of the center of an ellipsoidal model relative to the center of mass of the earth is not known. The positions determined on one datum cannot be related directly to positions on another datum. The development of absolutely-oriented datums incorporating satellite and gravity data has led to the development of datum transformations to relate positions on one datum to those on another. Sophisticated new electronic navigation and targeting technology requires highly precise input data to obtain output on the order of design accuracies. To obtain positions on the order of + / - 1000 feet/300 meters, care should be taken by the users of such equipment that the datum to which positions are referred is taken into account. If positions are located on two different datums, then the user must know that one set of coordinates must be transformed into the other system prior to their input into the inertial navigation system as a point of departure and a destination. This paper reviews some basic practical and theoretical concepts of datum development and evaluates errors that may be encountered if a datum transformation is required but is not used. Hardware and software alone cannot minimize the occurrence of these errors. The user community must be educated in the basic concepts of position determination. Therefore, this work is presented in such a manner as to be readily adapted to teach users of varying backgrounds, education and expertise.
Published in: NAVIGATION: Journal of the Institute of Navigation, Volume 30, Number 3
Pages: 252 - 260
Cite this article: Robinson, Gregory A., Miller, David E., "THE INFLUENCE OF REFERENCE SYSTEM DISPARITY ON NAVIGATION AND POSITIONING", NAVIGATION: Journal of The Institute of Navigation, Vol. 30, No. 3, Fall 1983, pp. 252-260.
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